Benadryl is widely known as an anti-allergy medication. It is a handy medicine for humans and dogs alike who are suffering mild to severe allergies. Although Benadryl may be used for dogs, you must consult your vet for proper dosage and assess if it is an appropriate medication for your dog.

What's Benadryl

Benadryl is an anti-allergy or antihistamine that helps calm allergic reactions. This may include allergies from insect bites, food allergies, medication allergies, and other environmental allergies. It is easily purchased over-the-counter making it an accessible solution to allergies. It’s the most active ingredient is diphenhydramine. This ingredient blocks histamine that causes inflammations and other reactions to allergens.  Although Benadryl is generally made for humans, vets frequently recommend the use of Benadryl for dogs with allergies.

Before giving your dog Benadryl make sure he is not sensitive or allergic to any other components that might be included like cetirizine, acetaminophen, and others.


Benadryl is generally used for allergies, but can also be given for other issues.


The usual symptoms of allergies are runny nose, watery eyes, and sneezing. With dogs, allergies are more prone to show through the skin, nasal discharge, inflamed eyes, coughing, and itchiness. Having a check-up is best to eliminate the possibility of having other underlying conditions that cause these symptoms similar to allergies.

Also as there are many types of allergies like seasonal allergies, food allergies, or insect bites, your vet can determine what allergens are causing symptoms to your pet.


Hives are caused by many varying health conditions. Benadryl is your quick and instant relief but not a cure. Your vet can prescribe you Benadryl to effectively combat unexpected hives breakout but he will give you other medication to directly target the cause of the allergies.

Motion Sickness

Benadryl can also be used for motion sickness in dogs. It also helps relax the mind and alleviate motion sickness.


Mast cell tumors cause a large amount of histamine to be released in the body creating severe allergies. If your dog has a tumor, Benadryl will be part of his medication to combat histamine symptoms. However, in this situation, you must consult with your veterinarian.


The general dose for puppies is 1mg of Benadryl for each 1lb of weight. A dog weighing 25lbs is generally given one 25mg Benadryl pill every 8-12 hours until the allergy is gone. Please check with your vet for the right dosage for your dog.


The side effects of Benadryl in dogs are much like the side effects of Benadryl in humans. These include nausea, sleepiness, rapid heartbeat, lack of appetite, and urinary retention. If your dog is undergoing any other treatment for other diseases or pregnant, consult your vet if there are any complications with the mix of medicines your dog is taking.

This is a really useful video containing some great tips for giving your dog antihistamines